Method for curing fluoroelastomer compositions containing fluoroaliphatic sulfonamides as curing agents

ABSTRACT

Vulcanizable fluorocarbon elastomer compositions containing a vinylidene fluoride copolymer and a fluoroaliphatic sulfonamide curing agent. A second curing agent selected from organic polyhydroxy compounds or derivatives thereof, and an organo-onium accelerator are also employed. The compositions of this invention can be used to prepare shaped articles that exhibit high tensile strength accompanied by high elongation and a low value of compression set.

This application is a divisional of U.S. application Ser. No.07/619,669, filed Nov. 28, 1990, now U.S. Pat No. 5,086,123, which is acontinuation of U.S. Ser. No. 07/376,886, filed Jul. 6, 1989, nowabandoned, which was a continuation-in-part of U.S. Ser. No. 654,191,filed Sep. 24, 1984, now abandoned which was a continuation-in-part ofU.S. Ser. No. 583,762, filed Feb. 27, 1984, now abandoned.

This invention relates to a method for vulcanizing fluorocarbonelastomers and vulcanizing agents for use therein. In another aspect,the invention relates to vulcanizable fluorocarbon elastomercompositions containing vinylidene fluoride polymers and vulcanizingagent and adjuvants. In a further aspect, this invention relates to theuse of fluoroaliphatic sulfonamide compounds along with polyhydroxidecompounds or polyamine compounds in the vulcanization of vinylidenefluoride polymers.

Among the polymers which are difficult to vulcanize are fluorocarbonelastomers prepared by the polymerization of vinylidene fluoride withother terminally unsaturated monoolefins, such as hexafluoropropene,1-hydropentafluoropropene, chlorotrifluoroethylene, tetrafluoroethylene,and fluorinated vinyl ethers, such as perfluoromethyl vinyl ether. Thevulcanized or cured fluorocarbon elastomers have valuable properties,such as acid and base resistance, thermal stability, high tensilestrength, low compression set, and good tear resistance. As such, thefluorocarbon elastomers have become polymers of choice for service asgaskets, seals, and O-rings in severe or harsh environments in theautomotive, aircraft, and chemical industries.

Presently used conventional vulcanizing (or curing) agents forfluorocarbon elastomers include aromatic polyhydroxy compounds, such aspolyphenols, which are usually used in combination with certainvulcanization accelerators, viz., organo-onium compounds, e.g.,ammonium, phosphonium, and sulfonium compounds. As is known, anorgano-onium compound is the conjugate acid of a Lewis base (e.g.,phosphine, amine, ether, or sulfide) and can be formed by reacting saidLewis base with a suitable alkylating agent (e.g., an alkyl halide oracyl halide) resulting in the expansion of the valence of the electrondonating atom of the Lewis base and a positive charge on theorgano-onium compound. Many of the organo-onium compounds useful asvulcanization accelerators contain at least one heteroatom, i.e., anon-carbon atom such as N, P, S, O, bonded to organic or inorganicmoieties. See, for example, U.S. Pat. Nos. 3,655,727 (Patel et al),3,712,877 (Patel et al), 3,857,807 (Komatani), 3,686,143 (Bowman),3,933,732 (Schmiegel), 3,876,654 (Pattison), 4,233,421 (Worm), 4,250,278(Suzuki et al), 4,259,463 (Moggi et al), and 4,358,559 (Holcomb et al);and also see West, A. C. and Holcomb, A. G., "Fluorinated Elastomers",Kirk-Othmer: Encyclopedia of Chemical Technology, Vol. 8, 3rd Ed., JohnWiley & Sons, Inc., pp. 500-515 (1979). In addition to the vulcanizingaccelerators, divalent metal oxides or hydroxides (as inorganic acidacceptors), fillers, processing aids, and other adjuvants are alsoconventionally employed in the vulcanization of fluorocarbon elastomercompositions.

Although conventionally vulcanized fluorocarbon elastomers have manyuseful properties, as mentioned above, they generally do not havesufficiently high tensile strength combined with sufficiently highelongation for certain applications. Such applications where hightensile strength, high elongation fluorocarbon elastomers would beespecially useful include blowout preventers for oil wells, accumulatorbladders, and diaphragms. Although increasing the cross-link density ofcured elastomers will increase the tensile strength thereof, such anapproach often adversely affects the elongation of the elastomer. Thisinvention relates to the achievement of high tensile strengthaccompanied by high elongation in cured fluorocarbon elastomers by usinga novel vulcanizing, or curing agent which does not adversely affect theother desired properties of the cured fluorocarbon elastomer.

Briefly, in one aspect of this invention, fluorocarbon elastomers arevulcanized by using as a novel vulcanizing agent a compositioncomprising a fluoroaliphatic sulfonamide curing agent. These curingagents preferably have one or two sulfonamido groups.

Preferred classes of the fluoroaliphatic sulfonamide curing agentsuseful in the practice of this invention can be represented by thefollowing general formula:

    R.sub.f (A).sub.z SO.sub.2 NR(M.sub.1/x)                   I

or

    R.sub.f '[(A).sub.z SO.sub.2 NR(M.sub.1/x)].sub.2          II

wherein

R_(f) represents a monovalent fluoroaliphatic radical having, forexample, from 1 to 20 carbon atoms, preferably 4 to 10 carbon atoms,

R_(f) ' represents a divalent fluoroaliphatic radical having, forexample, from 1 to 20 carbon atoms, preferably from 2 to 10 carbonatoms,

A represents an organic linkage such as --CR¹ R² --, --CR¹ R² CR³ R⁴ --,and --CR¹ ═CR² --, wherein R¹,R²,R³, and R⁴ are selected from the groupconsisting of hydrogen atom, fluorine atom, chlorine atom, and loweralkyl group, having, for example, 1 to 2 carbon atoms,

z is zero or one,

R represents hydrogen atom or alkyl radical having, for example, from 1to 20 carbon atoms, preferably 1 to 12 carbon atoms, and

M represents hydrogen atom or salt forming cation with valence x, whichis 1, 2, or 3.

The monovalent fluoroaliphatic radical, R_(f), is a fluorinated, stable,inert, non-polar, saturated moiety. It can be straight chain, branchedchain, and, if sufficiently large, cyclic, or combinations thereof, suchas alkyl cycloaliphatic radicals. Generally, R_(f) will have 1 to 20carbon atoms, preferably 4 to 10, and will contain 40 to 83 weightpercent, preferably 50 to 78 weight percent fluorine. The preferredcompounds are those in which the R_(f) group is fully or substantiallycompletely fluorinated, as in the case where R_(f) is perfluoroalkyl,C_(n) F_(2n+1), where n is 1 to 20.

The divalent fluoroaliphatic radical, R_(f) ', is a fluorinated, stable,inert, non-polar, saturated moiety. It can be straight chain, branchedchain, and, if sufficiently large, cyclic, or combinations thereof, suchas alkylcycloaliphatic diradicals. Generally, R_(f), will have 1 to 20carbon atoms, preferably 2 to 10. The preferred compounds are those inwhich the R_(f), group is fully or substantially completely fluorinated,as in the case where R_(f) ' is perfluoroalkyl, C_(n) F_(2n), where n is1 to 20, or perfluorocycloalkyl, C_(n) F_(2n-2), where n is 5 to 20.

With respect to either R_(f) or R_(f) ', the skeletal chain or carbonatoms can be interrupted by divalent oxygen or trivalent nitrogen heteroatoms, each of which is bonded only to carbon atoms, but preferablywhere such hetero atoms are present, such skeletal chain does notcontain more than one said hetero atom for every two carbon atoms. Anoccasional carbon-bonded hydrogen atom, or chlorine atom may be present;where present, however, they preferably are present not more than oncefor every two carbon atoms in the chain. Where R_(f) or R_(f) ' is orcontains a cyclic structure, such structure preferably has 5 or 6 ringmember atoms, 1 or 2 of which can be said hetero atoms, i.e., oxygenand/or nitrogen. Examples of R_(f) radicals are fluorinated alkyl, e.g.,C₆ F₁₃ --, C₈ F₁₇ --, alkoxyalkyl, e.g., C₃ F₇ OCF₂ --. Examples ofR_(f) ' are fluorinated alkylene, e.g., --C₄ F₈ --, --C₆ F₁₂ --. WhereR_(f) is designated as a specific radical, e.g., C₈ F₁₇ --, it should beunderstood that this radical can represent an average structure of amixture, e.g., C₆ F₁₃ -- to C₁₀ F₂₁ --, which mixture can also includebranched structures.

Where R is an alkyl radical, it can be unsubstituted or substituted.Useful substituents include, for example, carbonyl groups, e.g.,##STR1## epoxy groups, e.g., ##STR2##

The fluorocarbon elastomers or gums, e.g., copolymers of vinylidenefluoride and hexafluoropropene, can be compounded with thefluoroaliphatic sulfonamide curing agent and the polyhydroxy orpolyamine curing agent and the vulcanizing adjuvants commonly used invulcanizing such elastomers, namely vulcanization accelerators, such asthe aforementioned organoammonium, phosphonium, and sulfonium compounds,e.g., triphenylbenzylphosphonium chloride, divalent metal oxides orhydroxides (as acid acceptors), e.g., MgO and Ca(OH)₂, and reinforcingagents or fillers, e.g., carbon black and silica. The thus compoundedelastomer or gumstock can then be shaped, e.g., by molding or extruding,in the form of seals, O-rings, gaskets, or other molded or extrudedparts or goods, and heat applied to effect vulcanization (or curing orcross-linking), to produce a shaped elastomeric article with desirabletensile strength and elongation and other desirable properties, such ashardness, tear strength, and a low value of permanent deformation, i.e.,compression set. Prior to the discovery of the composition of thepresent invention, it had been extremely difficult to efficientlyprepare from a fluorocarbon elastomer gum a shaped elastomeric articlehaving an acceptable value of elongation and a low value of compressionset.

Fluoroaliphatic sulfonamides suitable as curing agents in the practiceof this invention include known compounds [see, for example, U.S. Pat.No. 2,732,398 (Brice et al)]. They can be prepared by the reaction ofammonia or primary amines with perfluoroalkane sulfonyl fluorides(obtained by electrochemical fluorination of alkyl or alkylene sulfonylhalides), as shown by the following reaction scheme:

    R.sub.f SO.sub.2 F+RNH.sub.2 →R.sub.f SO.sub.2 NHR

They can also be prepared following the procedures described in U.S.Pat. No. 4,296,034 (Bouvet et al), i.e.,

    R.sub.f C.sub.2 H.sub.4 SO.sub.2 Cl+RNH.sub.2 →R.sub.f C.sub.2 H.sub.4 SO.sub.2 NHR

Salts of the sulfonamides can be prepared by reaction of the acidicsulfonamide compound with a suitable base, as described, for example, inU.S. Pat. No. 2,803,656 (Ahlbrecht et al):

    R.sub.f SO.sub.2 NHR+NaOCH.sub.3 →R.sub.f SO.sub.2 N(R)Na

Representative fluoroaliphatic sulfonamide compounds suitable for thepractice of this invention include the following:

CF₃ SO₂ NH₂

CF₃ SO₂ N(C₄ H₉)H

C₄ F₉ SO₂ N(CH₃)H

C₈ F₁₇ SO₂ N(CH₃)H

C₈ F₁₇ SO₂ N(CH₃)Na

C₈ F₁₇ C₂ H₄ SO₂ N(CH₃)Na

HN(CH₃)SO₂ (CF₂)₈ SO₂ N(CH₃)H

C₈ F₁₇ SO₂ NHNa

C₈ F₁₇ SO₂ N(C₁₂ H₂₅)H

C₆ F₁₃ SO₂ N(C₂ H₅)K

C₈ F₁₇ SO₂ N(C₆ H₅)H

C₄ F₉ CH₂ SO₂ N(CH₃)H

C₈ F₁₇ SO₂ N(CH₃)Mg_(1/2)

C₈ F₁₇ SO₂ N(CH₃)NH₄

C₈ F₁₇ SO₂ N(CH₃)N(C₂ H₅)₃ H

Curing agents that can be used in combination with the fluoroaliphaticsulfonamide curing agents of this invention for curing vinylidenefluoride copolymers include both the convention,al curing agents used tocure fluoroelastomers, i.e., polyhydroxy compounds or derivativesthereof, organic polyamines or derivatives thereof, and the recentlydeveloped curing agents such as fluoroaliphatic polyols and allyl ethersof aromatic polyhydroxy compounds. A second curing agent must beemployed when the fluoroaliphatic sulfonamide is monofunctional, i.e.,of the class of Formula I. Difunctional fluoroaliphatic sulfonamides,i.e., of the class of Formula II, can be used alone, that is, in theabsence of a second curing agent. Representative examples of theabove-mentioned second curing agents that can be used withmonofunctional fluoroaliphatic sulfonamides include:

hydroquinone

resorcinol

4,4'-dihydroxydiphenylsulfone (Bisphenol S)

2,4'-dihydroxydiphenylsulfone

2,2-isopropylidine-bis (4-hydroxybenzene) (Bisphenol A)

2,2-hexafluoroisopropylidine-bis

(4-hydroxybenzene) (Bisphenol AF)

4,4'-dihydroxybenzophenone

4,4'-biphenol

1-allyloxy-4-hydroxybenzene

Bisphenol A monoallyl ether

1,4-bis(hydroxymethyl) perfluorobutane

hexamethylenediamine carbamate

N,N'-dicinnamylidine-1,6-hexanediamine Mixtures of the foregoing canalso be used.

Organo-onium compounds suitable for use in this invention are known andare described in the art. Mixtures of organo-onium compounds are alsouseful in this invention. Classes of organo-onium compounds suitable forthis invention include quaternary organo-onium compounds, such as thoseselected from the group consisting of ammonium, arsonium, phosphonium,stibonium, amino-phosphonium, phosphorane (e.g., triarylphosphorane),and iminium compounds, and sulfonium compounds.

Organo-onium compounds which can be used as accelerators in thecompounded fluorocarbon elastomer compositions of this invention includethe following representative compounds and mixtures thereof:

triphenylbenzyl phosphonium chloride

tributylallyl phosphonium chloride

tributylbenzyl ammonium chloride

tetrabutyl ammonium bromide

triphenyl sulfonium chloride

tritolyl sulfonium chloride

8-benzyl-1,8-diazabicyclo [5,4,0]-7-undecenium chloride

benzyl tris (dimethylamino) phosphonium chloride

benzyl(diethylamino)diphenylphosphonium chloride

Organo-onium compounds that can be used as vulcanization accelerators inthe compositions of this invention are more completely described inassignee's copending application Ser. No. 311,135, filed Feb. 15, 1989,incorporated herein by reference.

The polymers that are vulcanizable or curable according to thisinvention are known linear, saturated, thermoplastic, fluorinatedpolymers or gums which can be classified as fluorocarbon elastomers.Such polymers are described, for example, in the aforementioned priorart, e.g., U.S. Pat. Nos. 4,233,421 (Worm) and 4,287,320 (Kolb). Many ofthese are commercially available, sold under trademarks such as"Fluorel" and "Viton", and are copolymers of vinylidene fluoride and oneor more other monoolefins (usually halogenated).

Among the polymers that can be vulcanized in accordance with thisinvention are the elastomeric copolymers of vinylidene fluoride withmonomers selected from, for example, hexafluoropropene,chlorotrifluoroethylene, 2-chloropentafluoropropene, fluorinated alkylvinyl ether, e.g., perfluoromethyl vinyl ether, tetrafluoroethylene,1-hydropentafluoropropene, dichlorodifluoroethylene, trifluoroethylene,and 1,1-chlorofluoroethylene. These monoolefins can be copolymerizedwith each other in groups of two or more. They can also be copolymerizedwith other olefinic compounds such as ethylene or propylene. Thepreferred elastomers are copolymers of vinylidene fluoride with at leastone terminally unsaturated fluoromonoolefin containing at least onefluorine atom substituent on each double-bonded carbon atom, each carbonatom of said fluoromonoolefin being substituted only with fluorine,chlorine, hydrogen, lower fluoroalkyl radical, or lower fluoroalkoxyradical, particularly hexafluoropropene, tetrafluoroethylene,chlorotrifluoroethylene, and 1-hydropentafluoropropene. Particularlypreferred are the fluorocarbon elastomers produced by copolymerizingvinylidene fluoride with hexafluoropropene as described in U.S. Pat.Nos. 3,051,677 and 3,318,854 and those copolymers produced bycopolymerizing vinylidene fluoride, hexafluoropropene, andtetrafluoroethylene as described in U.S. Pat. No. 2,968,649. Theelastomeric copolymers of hexafluoropropene and vinylidene fluoridehaving between about 15 and about 50 mole percent hexafluoropropene,optionally with the addition of up to 30 mole percenttetrafluoroethylene, are illustrative of this preferred class. Mixturesor blends of fluorinated elastomers, e.g., of different viscosities, arealso suitable.

When used as the sole curing agent, a sufficient amount of difunctionalfluoroaliphatic sulfonamide curing agent must be used in order to bringabout cross-linking of the fluorocarbon elastomer gum. In general, thisamount is at least 0.001 mhr (moles per 100 grams fluorocarbonelastomer, gum, or rubber).

When monofunctignal fluoroaliphatic sulfonamide curing agent and asecond curing agent are used in combination to cure the fluorocarbonelastomer, the total amount of both must be sufficient to bring aboutcross-linking of the fluorocarbon elastomer. This requirement is alsoapplicable when difunctional fluoroaliphatic curing agent and a secondcuring agent are used in combination. A sufficient amount offluoroaliphatic sulfonamide curing agent must be used with the secondcuring agent in order to provide sufficient cross-linking to provideimproved properties, e.g., increased tensile strength, reducedcompression set, when compared with the properties obtained in theabsence of fluoroaliphatic sulfonamide curing agent. The amount ofmonofunctional fluoroaliphatic sulfonamide curing agent, e.g., C₈ F₁₇SO₂ N(CH₃)H, that can be used with the conventional curing agents, e.g.,polyhydroxy compounds, in the curing of fluorocarbon elastomers in thepresent invention, ranges from about 0.0002 mhr to about 0.006 mhr. Theamount of the conventional curing agent used in conjunction with thefluoroaliphatic sulfonamide will be about 0.0005 mhr to about 0.01 mhr.The total concentration of the curing agents must be at least 0.001 mhr.In general, increasing the concentration of the fluoroaliphaticsulfonamide curing agent and conventional curing agent, will result in amore highly cross-linked fluorocarbon elastomer.

Assignee's U.S. Pat. No. 3,632,788 discloses a composition comprising acopolymer of perfluoropropene and vinylidene fluoride or a terpolymer ofperfluoropropene, vinylidene fluoride and tetrafluoroethylene andcontaining highly fluorinated fluid plasticizer in excess of theordinary compatibility limit therein but in amounts less than about 280parts by weight for each 100 parts of the elastomer, at least onecompatibility extender comprising a low molecular weight, polar,fluoroaliphatic compound containing at least one polar group andcontaining at least 45% by weight of fluorine in the form of at leastone fluoroaliphatic radical, said fluoroaliphatic compound having amelting point in the range of 50° C. to 200° C., said compatibilityextender content being from about 0.5 to about 2 parts by weight pereach part by weight of said plasticizer excess.

The composition of that patent uses a diamine as a curing agent and afluoroaliphatic sulfonamide as a compatibility extender. The use of adiamine as a curing agent results in the cured fluorocarbon gum having avalue of compression set that is unacceptable for such products asO-rings for high pressure applications (see Encyclopedia of PolymerScience and Engineering, Vol. 7, John Wiley & Sons (1987), pp. 262-267).The use of the curing system of the present invention, i.e., polyhydroxycompound, organo-onium accelerator, and fluoroaliphatic sulfonamide,provides cured fluorocarbon elastomer gums having both an acceptablevalue of compression set and an acceptable value of elongation.

The fluoroaliphatic sulfonamide curing agents of this invention, othercuring agents, accelerators, acid acceptors, reinforcing agents,fillers, and other adjuvants such as processing aids, softeners,plasticizers, etc. can be incorporated into the fluorocarbon elastomergum in the conventional manner.

Objects and advantages of this invention are illustrated in the examplesdescribed hereinafter. In those examples, curing conditions andproperties of cured compounded gumstock were measured using thefollowing procedures and test methods:

Curing Characteristics

ASTM D-2048-82 was run on uncured compounded gumstock using theOscillating Disc Rheometer (ODR) Model 100S (Monsanto Company), anoscillating frequency of 100 cpm and a 3° arc. Minimum torque (M_(L))and the torque attained at a stated time (M_(H)) were determined. Alsodetermined were time in minutes for torque to increase 0.1N·m(1 lbf·in),t_(s1), or time for torque to reach 5.6 N·m (50 lbf·in), t₅.6,respectively.

Press Cure

Elastomer sheets 150 mm×150 mm×1.8 mm were prepared for determination ofphysical properties by pressing uncured compounded gumstock at about6.9×10³ kPa for the indicated time at 177° C.

Post Cure

Samples were removed from the press and placed in a circulating airoven. The oven was maintained at the indicated temperature for theindicated time. The samples were then removed, cooled to roomtemperature, and physical properties determined.

Accelerated Aging

Post cured samples were placed in a circulating air oven for theindicated time at 275° C. The samples were then removed for measurementof physical properties according to ASTM D 573-81.

Tensile Strength at Break, Elongation at Break, Modulus at 100%Elongation

Samples cut from a 1.8 mm thick cured elastomer sheet were testedaccording to ASTM D-412-80 using the TENSOMETER, Model 500 (MonsantoCompany) with a die having the following dimensions: A=3.5 mm, L=19 mm,C=51 mm.

Hardness, Shore A

Hardness was measured at room temperature on cured samples according toASTM D-2240-81 using Shore Instrument and Mfg. Co.'s "A-2" device.

Compression Set

Tests according to ASTM D-395-78, Method B, were run on O-rings afterthe indicated press and post cures and the indicated temperature andtime under compression. Results are reported as percent (%) change indimension from original.

The fluoroaliphatic sulfonamides employed in the following examples wereprepared from the corresponding sulfonyl fluoride compounds by reactionwith ammonia or an alkyl amine. A subsequent reaction with alkali metalmethoxides yielded the salt. Preparation of the fluoroaliphaticsulfonamides and their salts followed the general procedure described inExample 1 of U.S. Pat. No. 2,803,656 (Ahlbrecht et al). The magnesiumsalt was prepared in a similar manner by reaction of magnesium methoxidewith the fluoroaliphatic sulfonamide. The ammonium and triethylammoniumsalts were prepared by reacting the fluoroaliphatic sulfonamide withexcess liquid ammonia and excess triethylamine, respectively.

In all of the following examples, the terms "parts" and "phr" representweight in grams and grams per hundred parts gum, elastomer, or rubber,respectively, and "mhr" represents moles per 100 parts gum, elastomer,or rubber.

Curing agents not of the fluoroaliphatic sulfonamide class and cureaccelerators employed in the following examples are listed in Tables Iand II, respectively.

                  TABLE I                                                         ______________________________________                                        Curing agents                                                                 No.  Designation Chemical identity                                            ______________________________________                                        1    Bisphenol AF                                                                              4,4'-HOC.sub.6 H.sub.4 C(CF.sub.3).sub.2 C.sub.6 H.sub.4                      OH                                                           2    Bisphenol S 4,4'-HOC.sub.6 H.sub.4 SO.sub.2 C.sub.6 H.sub.4 OH           3    Biphenol C  4,4'-HOC.sub.6 H.sub.4 COC.sub.6 H.sub.4 OH                  4    HQ          1,4-HOC.sub.6 H.sub.4 OH                                     5    Biphenol    4,4'-HOC.sub.6 H.sub.4 --C.sub.6 H.sub.4 OH                  6    Bisphenol   a. HOC.sub.6 H.sub.4 C(CH.sub.3).sub.2 C.sub.6 H.sub.4                        OH                                                                A-AE (mixture                                                                             b. HOC.sub.6 H.sub.4 C(CH.sub.3).sub.2 C.sub.6 H.sub.4                        OCH.sub.2 CH═CH.sub.2                                         of components                                                                             c. CH.sub.2 ═CHCH.sub.2 OC.sub.6 H.sub.4 C(CH.sub.3).                     sub.2 --                                                          a:b:c in 1.1:1.6:1                                                                        C.sub.6 H.sub.4 OCH.sub.2 CH═CH.sub.2                         weight ratio)                                                            7    FC-diol     HOCH.sub.2 (CF.sub.2).sub.4 CH.sub.2 OH                      ______________________________________                                    

                  TABLE II                                                        ______________________________________                                        Cure accelerators                                                             No.    Designation   Chemical identity                                        ______________________________________                                        1      TPBPC         (C.sub.6 H.sub.5).sub.3 P(CH.sub.2 C.sub.6 H.sub.5).s                         up.+ Cl.sup.-                                            2      TBBAC         (C.sub.4 H.sub.9).sub.3 N(CH.sub.2 C.sub.6 H.sub.5).s                         up.+ Cl.sup.-                                            3      TTSC          [(CH.sub.3)C.sub.6 H.sub.4 ].sub.3 S.sup.+ Cl.sup.-      ______________________________________                                    

EXAMPLE 1

A vinylidene fluoride copolymer gum (FKM C) was compounded on a two-rollrubber mill with a low level of a conventional vulcanizing agent and anormal level of adjuvants. FKM C contains 80 mole percent CF₂ =CH₂ and20 mole percent CF₃ CF═CF₂. In one of the runs, a fluoroaliphaticsulfonamide curing agent of this invention was incorporated into theformulation. A control run, i.e., a formulation without afluoroaliphatic sulfonamide curing agent, was also run for the purposeof comparison. The milled, compounded gumstocks were evaluated forcuring characteristics, and properties of the cured gumstocks weremeasured after press cure, post cure, and aging.

Curable gumstock compositions, curing characteristics, and properties ofcured gumstocks are shown in Table III.

                  TABLE III                                                       ______________________________________                                                             Run no.                                                                       1      2                                                 ______________________________________                                        Curable gumstock ingredients                                                  FKM C, high viscosity gum, part                                                                      100      100                                           Carbon black (N-110), phr                                                                            25       25                                            Ca(OH).sub.2, phr      6        6                                             TPBPC, mhr × 10.sup.3                                                                          1.4      0.77                                          Bisphenol AF, mhr × 10.sup.3                                                                   0.625    0.625                                         C.sub.8 F.sub.17 SO.sub.2 N(CH.sub.3)Na, mhr × 10.sup.3                                        0        2.81                                          Curing characteristics                                                        ODR, 177° C.:                                                          M.sub.L, N · m                                                                              4.86     5.20                                          M.sub.H, N · m, 12 minutes                                                                  5.54     5.99                                          t.sub.sl, minutes      3        2.1                                           t.sub.5.6, minutes     8        5.0                                           Properties of cured gumstock                                                  Press cure properties (2.5 hrs/177° C.)                                Tensile strength, MPa  7.51     20.04                                         Elongation at break, % 718      550                                           Modulus, 300%, MPa     4.79     9.51                                          Post cure properties (20 hrs/177° C.)                                  Tensile strength, MPa  10.42    21.63                                         Elongation at break, % 550      411                                           Modulus, 300%, MPa     7.31     15.24                                         Hardness, Shore A      78       76                                            Tear resistance, kN/m  26       28                                            (ASTM D 624-81, Die C, 25° C.)                                         ______________________________________                                    

Faster cure rates, considerably higher tensile strengths and modulus,and improved tear resistance were obtained in Run 2. Relatively highelongations were maintained in Run 2 even at the high tensile strengthsachieved.

EXAMPLE 2

A vinylidene fluoride copolymer gum (FKM C) was compounded in severaldifferent runs on a two-roll rubber mill with a conventional vulcanizingagent and adjuvants. In nine of the runs, a fluoroaliphatic sulfonamidecuring agent suitable for use in this invention was incorporated intothe formulation. The fluoroaliphatic sulfonamide curing agents were allin the form of a salt, except for Run 12. The amounts of the variousingredients are shown in Table IV.

                  TABLE IV                                                        ______________________________________                                        Curable gumstock ingredients                                                  ______________________________________                                        FKM C, parts         100                                                      Carbon black (N-990), phr                                                                          30                                                       MgO, phr             3                                                        Ca(OH).sub.2, phr    6                                                        TPBPC, mhr × 10.sup.3                                                                        1.22                                                     Bisphenol AF, mhr × 10.sup.3                                                                 2.23                                                     Fluoroaliphatic sulfonamide                                                                        1.22                                                     curing agent, mhr × 10.sup.3                                            ______________________________________                                    

The fluoroaliphatic sulfonamide curing agent for each run is listedbelow:

    ______________________________________                                        Run no.      Curing agent                                                     ______________________________________                                        3            Control                                                          4            C.sub.8 F.sub.17 SO.sub.2 N(CH.sub.3)Na                          5            C.sub.4 F.sub.9 SO.sub.2 N(CH.sub.3)Na                           6            C.sub.8 F.sub.17 SO.sub.2 N(C.sub.4 H.sub.9)Na                   7            H(CH.sub.3)NSO.sub.2 (CF.sub.2).sub.8 SO.sub.2 N(CH.sub.3)Na     8            C.sub.8 F.sub.17 C.sub.2 H.sub.4 SO.sub.2 N(CH.sub.3)Na          9            C.sub.8 F.sub.17 SO.sub.2 N(H)Na                                 10           C.sub.8 F.sub.17 SO.sub.2 N(CH.sub.3)(Mg).sub.1/2                11           C.sub.8 F.sub.17 SO.sub.2 N(CH.sub.3)NH.sub.4                    12           C.sub.8 F.sub.17 SO.sub.2 N(CH.sub.3)N(C.sub.2 H.sub.5).sub.3                  H                                                               ______________________________________                                    

The milled, compounded gumstocks were evaluated for curingcharacteristics, and properties of the cured gumstocks were measuredafter press cure, post cure, and aging. Compression set was alsodetermined. A control run (Run 3), i.e., a formulation without afluoroaliphatic sulfonamide curing agent, was also run for the purposeof comparison.

Curing characteristics of the uncured gumstock compositions, andproperties of cured gumstocks, are shown in Table V.

                                      TABLE V                                     __________________________________________________________________________                        Run no.                                                                       3   4   5   6   7   8    9   10   11  12                  __________________________________________________________________________    Curing characteristics                                                        ODR, 177° C.:                                                          M.sub.L, N · m                                                                           1.92                                                                              1.92                                                                              2.03                                                                              2.03                                                                              1.69                                                                              1.92 1.36                                                                              1.92 1.81                                                                              1.69                M.sub.H, N · m (12 minutes)                                                              3.62                                                                              6.33                                                                              6.21                                                                              5.65                                                                              7.91                                                                              4.75 3.95                                                                              6.33 6.55                                                                              5.88                t.sub.sl, minutes   2.0 1.3 1.3 1.5 2.0 1.8  3.1 1.8  1.7 1.7                 t.sub.5.6, minutes  --  2.6 2.6 7.0 3.4 --   --  3.6  3.2 3.4                 Properties of cured gumstock                                                  Press cure properties (10 min./177° C.):                               Tensile strength, MPa                                                                             7.37                                                                              9.29                                                                              9.60                                                                              9.53                                                                              9.86                                                                              9.02 8.71                                                                              9.79 9.12                                                                              9.94                Elongation at break, %                                                                            730 427 409 456 374 536  646 464  376 446                 Modulus, 100%, MPa  1.91                                                                              2.46                                                                              2.45                                                                              2.34                                                                              3.23                                                                              2.16 1.92                                                                              2.36 2.52                                                                              2.26                Hardness, Shore A   66  67  67  67  68  67   66  67   66  66                  Postcure properties (20 hrs/260° C.):                                  Tensile strength, MPa                                                                             8.15                                                                              12.66                                                                             13.29                                                                             12.07                                                                             12.51                                                                             10.92                                                                              11.80                                                                             13.47                                                                              10.62                                                                             12.18               Elongation at break, %                                                                            517 283 297 270 242 386  337 312  247 274                 Modulus, 100%, MPa  2.02                                                                              2.96                                                                              2.88                                                                              2.93                                                                              3.57                                                                              2.60 2.43                                                                              2.79 2.03                                                                              2.69                Hardness Shore A    68  68  67  67  69  67   67  68   67  67                  Aging Properties (70 hrs/275° C.):                                     Tensile strength, MPa                                                                             3.81                                                                              6.03                                                                              6.90                                                                              7.31                                                                              7.18                                                                              4.97 6.79                                                                              7.61 7.69                                                                              8.42                Elongation at break, %                                                                            640 326 327 287 248 500  393 311  285 265                 Modulus, 100%, MPa  1.60                                                                              2.23                                                                              2.36                                                                              2.68                                                                              3.05                                                                              1.99 2.05                                                                              2.78 3.03                                                                              3.16                Hardness, Shore A   70  70  68  71  72  69   71  71   70  70                  Compression set (70 hrs/200° C.), %                                                        52.8                                                                              28.2                                                                              27.5                                                                              35.5                                                                              30.6                                                                              42.6 33.0                                                                              --   --  --                  __________________________________________________________________________

In control Run 3, wherein no fluoroaliphatic sulfonamide was present,torque obtained after 12 minutes in the ODR test was lower than that inruns wherein fluoroaliphatic sulfonamide was present. In addition, lowertensile strength and modulus were observed for press cured, post curedand aged fluorocarbon elastomer in Run 3 than for fluorocarbonelastomers in runs utilizing fluoroaliphatic sulfonamide. Moreover, veryhigh elongation and a high compression set indicated a low state of curefor the fluorocarbon elastomer in Run 3.

EXAMPLE 3

Following the procedure of Example 2, four compounded curablefluorocarbon elastomer gumstocks were prepared. In Runs 14-17, thegumstock contained a fluoroaliphatic sulfonamide curing agent suitablefor use in this invention in the free non-salt form. The identities andquantities of the various ingredients are shown in Table VI.

                  TABLE VI                                                        ______________________________________                                        Curable gumstock ingredients                                                                       Parts                                                    ______________________________________                                        FKM C, parts         100                                                      Carbon black (N-990), phr                                                                          30                                                       MgO, phr             3                                                        Ca(OH).sub.2, phr    6                                                        TPBPC, mhr × 10.sup.3                                                                        1.22                                                     Bisphenol AF, mhr × 10.sup.3                                                                 2.23                                                     Fluoroaliphatic sulfonamide                                                                        1.22                                                     curing agent, mhr × 10.sup.3                                            ______________________________________                                    

The fluoroaliphatic sulfonamide curing agent for each run is listedbelow:

    ______________________________________                                        Run no.         Curing agent                                                  ______________________________________                                        13              Control                                                       14              C.sub.8 F.sub.17 SO.sub.2 N(CH.sub.3)H                        15              C.sub.4 F.sub.9 SO.sub.2 N(CH.sub.3)H                         16              C.sub.8 F.sub.17 SO.sub.2 N(C.sub.12 H.sub.25)H               17              C.sub.8 F.sub.17 C.sub.2 H.sub.4 SO.sub.2 N(CH.sub.3)H        ______________________________________                                    

Curing characteristics of the uncured gumstocks, and properties of thecured gumstocks were determined and are shown in Table VII.

                  TABLE VII                                                       ______________________________________                                                   Run no.                                                                       13    14      15      16    17                                     ______________________________________                                        Curing characteristics                                                        ODR, 177° C.:                                                          M.sub.L, N · m                                                                    1.92    2.05    1.86  1.82  1.81                                 M.sub.H, N · m,                                                                   3.62    6.44    6.33  5.76  3.84                                 12 minutes                                                                    t.sub.sl, minutes                                                                          2.0     1.5     1.6   1.8   1.5                                  t.sub.5.6, minutes                                                                         --      2.9     3.1   6.0   --                                   Properties                                                                    of cured gumstock                                                             Press cure properties                                                         (10 min/177° C.):                                                      Tensile strength, MPa                                                                      7.37    9.47    9.68  9.35  7.97                                 Elongation at                                                                              730     373     424   459   649                                  break, %                                                                      Modulus, 100%, MPa                                                                         1.91    2.49    2.46  2.27  2.02                                 Hardness, Shore A                                                                          66      67      67    67    66                                   Post cure properties                                                          (20 hrs/260° C.):                                                      Tensile strength, MPa                                                                      8.15    11.55   12.97 12.35 8.78                                 Elongation at                                                                              517     267     281   291   445                                  break, %                                                                      Modulus, 100%, MPa                                                                         2.02    2.88    2.89  2.73  2.50                                 Hardness, Shore A                                                                          68      67      67    67    68                                   Aging properties                                                              (70 hrs/275° C.):                                                      Tensile strength, MPa                                                                      3.81    7.37    7.18  7.13  --                                   Elongation at                                                                              640     331     326   268   --                                   break, %                                                                      Modulus, 100%, MPa                                                                         1.60    2.43    2.25  2.63  --                                   Hardness, Shore A                                                                          70      68      70    71    --                                   Compression set                                                                            52.8    30.2    26.3  38.6  --                                   (70 hrs/200° C.)                                                       ______________________________________                                    

Generally higher tensile strength and modulus were observed for thecured gumstocks containing fluoroaliphatic sulfonamide curing agent (seeRuns 14-17).

EXAMPLE 4

Following the procedure of Example 2, fourteen compounded curablefluorocarbon elastomer gumstocks were prepared containing variousconventional organic dihydroxy curing agents. In one-half of the runs,the gumstocks contained a fluoroaliphatic sulfonamide curing agentsuitable for use in this invention. The other runs were comparativeruns. The identities and amounts of the various ingredients are shown inTable VIII.

                                      TABLE VIII                                  __________________________________________________________________________                       Run no.                                                                       18 19 20 21 22 23 24 25 26 27 28 29  30 31                 __________________________________________________________________________    Curable gumstock ingredients                                                  FRM C, parts       100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100 100                                                                              100                Carbon black (N-990), phr                                                                        30 30 30 30 30 30 30 30 30 30 30 30  30 30                 MgO, phr           3  3  3  3  3  3  3  3  3  3  3  3   3  3                  Ca(OH).sub.2, phr  6  6  6  6  6  6  6  6  6  6  6  6   6  6                  TPBPC, mhr × 10.sup.3                                                                      1.22                                                                             1.22                                                                             1.22                                                                             1.22                                                                             1.22                                                                             1.22                                                                             1.22                                                                             1.22                                                                             1.22                                                                             1.22                                                                             1.22                                                                             1.22                                                                              1.22                                                                             1.22               Fluoroaliphatic sulfonamide                                                   curing agent                                                                  C.sub.8 F.sub.17 SO.sub.2 N(CH.sub.3)H, mhr × 10.sup.3                                     -- 1.22                                                                             -- 1.22                                                                             -- 1.22                                                                             -- 1.22                                                                             -- 1.22                                                                             -- 1.22                                                                              -- 1.22               Dihydroxy curing agents.sup.a                                                 Bisphenol AF, mhr × 10.sup.3                                                               6.50                                                                             6.50                                                                             -- -- -- -- -- -- -- -- -- --  -- --                 Bisphenol S, mhr × 10.sup.3                                                                -- -- 6.50                                                                             6.50                                                                             -- -- -- -- -- -- -- --  -- --                 Bisphenol C, mhr × 10.sup.3                                                                -- -- -- -- 6.50                                                                             6.50                                                                             -- -- -- -- -- --  -- --                 Bisphenol, mhr × 10.sup.3                                                                  -- -- -- -- -- -- 6.50                                                                             6.50                                                                             -- -- -- --  -- --                 HQ, mhr × 10.sup.3                                                                         -- -- -- -- -- -- -- -- 6.50                                                                             6.50                                                                             -- --  -- --                 Bisphenol A-AE mixture, mhr × 10.sup.3                                                     -- -- -- -- -- -- -- -- -- -- 3.80                                                                             3.80                                                                              -- --                 FC-diol, mhr × 10.sup.3                                                                    -- -- -- -- -- -- -- -- -- -- -- --  6.50                                                                             6.50               __________________________________________________________________________     .sup.a Structures of cocuring agents are shown in Table I.               

Curing characteristics of the uncured gumstocks, and properties of thecured gumstocks were determined, and are shown in Table IX.

                                      TABLE IX                                    __________________________________________________________________________                        Run no.                                                                       18  19  20  21  22  23  24                                __________________________________________________________________________    Curing Characteristics                                                        ODR, 177° C.:                                                          M.sub.L, N · m                                                                           1.02                                                                              0.68                                                                              1.24                                                                              0.68                                                                              1.47                                                                              0.79                                                                              1.47                              M.sub.H, N · m; 12 minutes                                                               10.96                                                                             10.39                                                                             2.37                                                                              5.65                                                                              5.76                                                                              7.34                                                                              6.78                              t.sub.sl, minutes   6.0 5.0 7.2 6.0 4.8 4.8 3.0                               t.sub.5.6, minutes  8.7 7.0 --  11.9                                                                              11.6                                                                              7.6 13                                Properties of cured gumstock                                                  Press cure properties (10 min/177° C.):                                Tensile strength, MPa                                                                             9.45                                                                              10.91                                                                             8.93                                                                              10.70                                                                             8.94                                                                              11.02                                                                             7.96                              Elongation at break, %                                                                            235 229 401 320 318 274 259                               Modulus, 100%, MPa  4.32                                                                              4.58                                                                              2.72                                                                              3.16                                                                              2.96                                                                              3.44                                                                              3.36                              Hardness, Shore A   74  72  70  --  70  72  68                                Postcure properties (20 hrs/260° C.):                                  Tensile strength, MPa                                                                             14.84                                                                             15.18                                                                             12.07                                                                             15.28                                                                             12.31                                                                             13.17                                                                             9.31                              Elongation at break, %                                                                            172 158 288 218 248 191 177                               Modulus, 100%, MPa  6.83                                                                              6.89                                                                              3.31                                                                              4.46                                                                              3.67                                                                              4.58                                                                              4.41                              Hardness, Shore A   76  74  72  73  71  72  69                                 Aging properties (70 hrs/275° C.):                                    Tensile strength, MPa                                                                             9.47                                                                              9.89                                                                              8.38                                                                              10.40                                                                             7.79                                                                              9.45                                                                              5.39                              Elongation at break, %                                                                            206 157 382 265 346 224 266                               Modulus, 100%, MPa  4.27                                                                              5.49                                                                              2.47                                                                              3.21                                                                              2.49                                                                              3.43                                                                              2.61                              Hardness, Shore A   76  --  72  74  72  73  73                                Compression set (70 hrs/200° C.), %                                                        14.7                                                                              19.3                                                                              23.3                                                                              18.8                                                                              21.1                                                                              20.1                                                                              25.4                              __________________________________________________________________________                        Run no.                                                                       25  26  27  28  29  30  31                                __________________________________________________________________________    Curing Characteristics                                                        ODR, 177° C.:                                                          M.sub.L, N · m                                                                           0.68                                                                              1.47                                                                              1.24                                                                              1.81                                                                              1.69                                                                              2.37                                                                              1.92                              M.sub.H, N · m; 12 minutes                                                               9.72                                                                              7.00                                                                              8.81                                                                              2.26                                                                              3.73                                                                              4.29                                                                              9.38                              t.sub.sl, minutes   5.0 2.7 2.3 2.3 1.8 1.4 1.4                               t.sub.5.6, minutes  8   4.5 3.6 --  --  --  9.38                              Properties of cured gumstock                                                  Press cure properties (10 min/177° C.):                                Tensile strength, MPa                                                                             10.42                                                                             8.96                                                                              10.51                                                                             .sup. --.sup.a                                                                    10.34                                                                             5.56                                                                              10.30                             Elongation at break, %                                                                            214 299 258 --  594 526 269                               Modulus, 100% MPa   4.23                                                                              3.06                                                                              3.58                                                                              --  1.92                                                                              2.16                                                                              3.50                              Hardness, Shore A   69  67  67  --  64  66  69                                Postcure properties (20 hrs/260° C.):                                  Tensile strength, MPa                                                                             15.18                                                                             13.24                                                                             14.22                                                                             --  12.53                                                                             9.71                                                                              15.26                             Elongation at break, %                                                                            171 242 187 --  236 396 188                               Modulus, 100%, MPa  5.81                                                                              3.67                                                                              4.51                                                                              --  3.41                                                                              2.72                                                                              5.34                              Hardness, Shore A   70  67  67  --  68  68  70                                Aging properties (70 hrs/275° C.):                                     Tensile strength, MPa                                                                             8.63                                                                              6.55                                                                              9.13                                                                              --  7.67                                                                              --  10.96                             Elongation at break, %                                                                            159 348 216 --  207 --  198                               Modulus, 100%, MPa  4.85                                                                              2.19                                                                              3.54                                                                              --  3.45                                                                              --  3.67                              Hardness, Shore A   68  67  69  --  66  --  --                                Compression set (70 hrs./200° C.), %                                                       24.0                                                                              22.4                                                                              25.5                                                                              --  35.9                                                                              --  18.3                              __________________________________________________________________________     .sup.a poor cured properties                                             

In general, faster cure rates (as indicated by the value of t₅.6 and thehigher torque after 12 minutes in the ODR test), and higher tensilestrengths of cured elastomers were obtained for elastomer gumstockscontaining fluoroaliphatic sulfonamide curing agents.

EXAMPLE 5

Following the procedure of Example 2, six compounded curablefluorocarbon elastomer gumstocks were prepared containing variousconventional organo-onium cure accelerators. In one-half of the runs(33, 35, and 37), the gumstock contained a fluoroaliphatic sulfonamidecuring agent suitable for use in this invention. The other runs (32, 34,and 36) were comparative runs. The identities and amounts of the variousingredients are shown in Table X.

                                      TABLE X                                     __________________________________________________________________________                     Run no.                                                                       32  33  34  35  36  37                                       __________________________________________________________________________    Curable gumstock ingredients                                                  FKM C, parts     100 100 100 100 100 100                                      Carbon black (N-990), phr                                                                      30  30  30  30  30  30                                       MgO, phr         3   3   3   3   3   3                                        Ca(OH).sub.2, phr                                                                              6   6   6   6   6   6                                        Bisphenol AF, mhr × 10.sup.3                                                             2.23                                                                              2.23                                                                              2.23                                                                              2.23                                                                              2.23                                                                              2.23                                     C.sub.8 F.sub.17 SO.sub.2 N(CH.sub.3)Na, mhr × 10.sup.3                                  --  1.22                                                                              --  1.22                                                                              --  1.22                                     Cure accelerators.sup.a                                                       TPBPC, mhr × 10.sup.3                                                                    1.22                                                                              1.22                                                                              --  --  --  --                                       TBBAC, mhr × 10.sup.3                                                                    --  --  1.22                                                                              1.22                                                                              --  --                                       TTSC, mhr × 10.sup.3                                                                     --  --  --  --  1.22                                                                              1.22                                     __________________________________________________________________________     .sup.a See Table II for structures of cure accelerators.                 

Curing characteristics of the uncured gumstocks, and properties of thecured gumstocks were determined, and are shown in Table XI.

                                      TABLE XI                                    __________________________________________________________________________                        Run no.                                                                       32  33  34  35  36  37                                    __________________________________________________________________________    Curing characteristics                                                        ODR, 177° C.:                                                          M.sub.L, N · m                                                                           1.92                                                                              1.92                                                                              1.58                                                                              1.64                                                                              1.41                                                                              1.58                                  M.sub.H, N · m; 12 minutes                                                               3.62                                                                              6.33                                                                              2.82                                                                              5.65                                                                              2.60                                                                              --                                    t.sub.sl, minutes   2.0 1.3 2.1 1.9 3.3 2.9                                   t.sub.5.6, minutes  --  2.6 --  5.0 --  --                                    Properties of cured gumstock                                                  Press cure properties (10 min/177° C.):                                Tensile strength, MPa                                                                             7.37                                                                              6.33                                                                              7.65                                                                              9.84                                                                              4.20                                                                              9.23                                  Elongation at break, %                                                                            730 427 673 415 765 529                                   Modulus, 100%, MPa  1.91                                                                              2.46                                                                              2.03                                                                              2.65                                                                              1.63                                                                              2.16                                  Hardness, Shore A   66  67  67  68  65  66                                    Postcure properties (20 hrs/260° C.):                                  Tensile strength, MPa                                                                             8.15                                                                              12.66                                                                             8.80                                                                              12.45                                                                             4.95                                                                              11.87                                 Elongation at break, %                                                                            517 283 500 268 680 403                                   Modulus, 100%, MPa  2.02                                                                              2.96                                                                              2.26                                                                              3.11                                                                              1.81                                                                              2.34                                  Hardness, Shore A   68  68  67  67  67  67                                    Aging properties (70 hrs/275° C.):                                     Tensile strength, MPa                                                                             3.81                                                                              6.93                                                                              4.02                                                                              6.92                                                                              --  --                                    Elongation at break, %                                                                            640 326 521 280 --  --                                    Modulus, 100%, MPa  1.60                                                                              2.23                                                                              1.64                                                                              2.69                                                                              --  --                                    Hardness, Shore A   70  70  68  71  --  --                                    Compression set (70 hrs/200° C.), %                                                        52.8                                                                              28.2                                                                              66.8                                                                              36.1                                                                              --  --                                    __________________________________________________________________________

In general, faster cure rates, higher tensile strengths, and lowercompression sets of cured elastomers were obtained for elastomergumstocks containing fluoroaliphatic sulfonamide curing agents.

EXAMPLE 6

Following the general procedure of Example 1, four compounded curablefluorocarbon elastomer gumstocks were prepared, each containing twodifferent conventional curing agents, and, further containing, in Runs39 and 41, a fluoroaliphatic sulfonamide curing agent suitable for usein this invention. Runs 38 and 40 were comparative runs. The identitiesand amounts of the various ingredients are shown in Table XII.

                  TABLE XII                                                       ______________________________________                                                       Run no.                                                        Curable gumstock ingredients                                                                   38      39      40    41                                     ______________________________________                                        FKM C, parts     100     100     100   100                                    Carbon black (N-990), phr                                                                      30      30      30    30                                     MgO.sup.a, phr   15      15      15    15                                     DIAK No. 1.sup.b, mhr × 10.sup.3                                                         8.70    8.70    --    --                                     DIAK No. 3.sup.c, mhr × 10.sup.3                                                         --      --      8.70  8.70                                   C.sub.8 F.sub.17 SO.sub.2 N(CH.sub.3)H,                                                        --      1.86    --    1.86                                   mhr × 10.sup.3                                                          ______________________________________                                         .sup.a MAGLITE Y, commercially available from Merck                           .sup.b Hexamethylenediamine carbamate, .sup.+ H.sub.3 N(CH.sub.2).sub.6       NHCOO.sup.-                                                                   .sup.c N,Ndicinnamylidine-1,6-hexanediamine, (CH.sub.2).sub.6                 (N═CHCH═CHC.sub.6 H.sub.5).sub.2                                 

Curing characteristics and properties of cured gumstock are shown inTable XIII.

                  TABLE XIII                                                      ______________________________________                                                       Run no.                                                                       38    39      40      41                                       ______________________________________                                        Curing characteristics                                                        ODR, 177° C.:                                                          M.sub.L, N · m                                                                        1.92    1.81    0.90  1.13                                   M.sub.H, N · m; 12 minutes                                                            6.89    7.34    2.60  8.02                                   t.sub.sl, minutes                                                                              2.5     2.4     5.0   4.0                                    t.sub.5.6, minutes                                                                             7.0     6.4     --    7.8                                    Properties of cured gumstock                                                  Press cure properties                                                         (10 min/177° C.):.sup.a                                                Tensile strength, MPa                                                                          13.82   12.62   10.40 9.38                                   Elongation at break, %                                                                         268     242     520   300                                    Modulus, 100%, MPa                                                                             3.58    3.58    2.01  3.10                                   Hardness, Shore A                                                                              68      68      65    69                                     Postcure properties                                                           (16 hrs/260° C.):                                                      Tensile strength, MPa                                                                          13.20   11.34   9.98  10.31                                  Elongation at break, %                                                                         232     187     247   145                                    Modulus, 100%, MPa                                                                             4.06    4.54    3.18  6.40                                   Hardness, Shore A                                                                              71      73      74    83                                     ______________________________________                                         .sup.a Run 40 was press cured for 20 min. at 177° C.              

A faster cure rate and a more highly cross-linked cured elastomer, asindicated by a higher modulus (except press cured gumstock of Run 39)and a lower elongation at break, were obtained for elastomer gumstockscontaining fluoroaliphatic sulfonamide curing agents.

EXAMPLE 7

A vinylidene fluoride copolymer gum (FKM C) and a vinylidene fluorideterpolymer gum (FKM T) were compounded in several different runs on atwo-roll rubber mill with various conventional vulcanizing agents andadjuvants. FKM C contains 80 mole percent CF₂ ═CH₂ and 20 mole percentCF₃ CF═CF₂. FKM T contains 60 mole percent CF₂ ═CH₂, 20 mole percent CF₃CF═CF₂, and 20 mole percent CF₂ ═CF₂. In two of the runs, afluoroaliphatic sulfonamide curing agent suitable for use in thisinvention was incorporated into the formulation. The milled, compoundedgumstocks were evaluated for curing characteristics, and properties ofthe cured gumstocks were measured after press cure, post cure, andaging. Compression set was also determined. The runs and resultsobtained are shown in Table XIV. Control runs, i.e., formulationswithout fluoroaliphatic sulfonamide curing agent, were also run for thepurpose of comparison.

                  TABLE XIV                                                       ______________________________________                                                       Run no.                                                        Curable gumstock ingredients                                                                   42      43      44    45                                     ______________________________________                                        FKM C, parts     100     100     0     0                                      FKM T, parts     --      --      100   100                                    Carbon black (N-990), phr                                                                      30      30      30    30                                     MgO.sup.a, phr   3       3       3     3                                      Ca(OH).sub.2, phr                                                                              6       6       6     6                                      TPBPC.sup.b, mhr × 10.sup.3                                                              1.22    1.22    1.22  1.22                                   Bisphenol AF.sup.c, mhr × 10.sup.3                                                       6.49    6.49    6.49  6.49                                   C.sub.8 F.sub.17 SO.sub.2 N(CH.sub.3)Na,                                                       0       1.27    0     1.27                                   mhr × 10.sup.3                                                          ______________________________________                                         .sup.a MAGLITE D, commercially available from Merck                           .sup.b Cure accelerator No. 1 in Table II                                     .sup.c Curing agent No. 1 in Table I                                     

Curing characteristics and properties of cured gumstock are shown inTable XV.

                  TABLE XV                                                        ______________________________________                                                       Run no.                                                                       42    43      44      45                                       ______________________________________                                        Curing characteristics                                                        ODR, 177° C.:                                                          M.sub.L, N · m                                                                        1.02    0.96    2.26  1.92                                   M.sub.H, N · m, 12 min.                                                               11.1    11.5    10.8  12.2                                   t.sub.sl, minutes                                                                              5.3     4.0     4.1   5.1                                    t.sub.5.6, minutes                                                                             7.3     5.9     6.7   7.6                                    Properties of cured gumstock                                                  Press cure properties                                                         (10 min/177° C.):                                                      Tensile strength, MPa                                                                          8.62    9.39    9.78  8.45                                   Elongation at break, %                                                                         255     232     306   265                                    Modulus, 100% MPa                                                                              4.12    4.29    4.42  4.06                                   Hardness, Shore A                                                                              74      75      76    79                                     Postcure properties                                                           (20 hrs/260° C.):                                                      Tensile strength, MPa                                                                          14.70   13.48   15.42 14.91                                  Elongation at break, %                                                                         184     169     222   179                                    Modulus, 100%, MPa                                                                             6.45    6.37    5.90  6.89                                   Hardness, Shore A                                                                              76      77      80    82                                     Aging properties                                                              (70 hrs/275° C.):                                                      Tensile strength, MPa                                                                          9.71    10.01   8.06  8.01                                   Elongation at break, %                                                                         193     183     338   254                                    Modulus, 100%, MPa                                                                             4.84    4.83    3.14  3.96                                   Hardness, Shore A                                                                              77      77      80    82                                     Compression set  20      18      24    21.7                                   (70 hrs/200° C.), %                                                    ______________________________________                                    

A higher torque (M_(H)) was observed after 12 minutes for gumstockscontaining fluoroaliphatic sulfonamide curing agents (Runs 43 and 45). Alower compression set was also obtained for the elastomers of Runs 43and 45.

COMPARATIVE EXAMPLE A

The purpose of this comparative example is to show the properties of thecured composition described in U.S. Pat. No. 3,632,788. Run 46 employedthe composition used in Formulation D of the example of U.S. Pat. No.3,632,788. The composition of Run 47 was identical to that of Run 46with the exception that an organo-onium accelerator was employed. Thecomposition of Run 48 was identical to that of Run 47 with the exceptionthat the amine curing agent was omitted. The identities and amounts ofthe various ingredients are shown in Table XVI.

                  TABLE XVI                                                       ______________________________________                                                           Run no.                                                    Curable gumstock ingredients                                                                       46      47      48                                       ______________________________________                                        FKM C, parts         100     100     100                                      Carbon black (N-990), phr                                                                          15      15      15                                       PbO, phr             20      20      20                                       DIAK No. 1.sup.a, mhr × 10.sup.3                                                             6.25    6.25    0                                        TPBPC.sup.b, mhr × 10.sup.3                                                                  0       1.28    1.28                                     Fluoroether A, phr   27      27      27                                       C.sub.8 F.sub.17 SO.sub.2 N(C.sub.2 H.sub.5)C.sub.2 H.sub.4 OPO(OH).sub.2,                         30.72   30.72   30.72                                    mhr × 10.sup.3                                                          ______________________________________                                         .sup.a Hexamethylenediamine carbamate, .sup.+ H.sub.3 N(CH.sub.2).sub.6       NHCOO.sup.-                                                                   .sup.b Cure accelerator No. 1 in Table II                                

The compositions were mixed, press cured, oven cured, and aged under theconditions indicated in Table XVII. Curing characteristics andproperties of cured gumstock are shown in Table XVII.

                  TABLE XVII                                                      ______________________________________                                                            Run no.                                                                       46    47      48                                          ______________________________________                                        Curing characteristics                                                        ODR, 177° C.:                                                          M.sub.L, N · m                                                                             0.22    0.22    0.22                                    M.sub.H, N · m, 12 min.                                                                    0.22    0.33    0.22                                    t.sub.sl, minutes     *       12      *                                       t.sub.5.6, minutes    *       *       *                                       Properties of cured gumstock                                                  Press cure properties (10 min/177° C.):                                Tensile strength, MPa 5.05    3.91    **                                      Elongation at break, %                                                                              301     279     **                                      Modulus, 100% MPa     0.96    0.92    **                                      Hardness, Shore A     50      50      **                                      Postcure properties (20 hrs/260° C.):                                  Tensile strength, MPa 7.42    5.99    **                                      Elongation at break, %                                                                              360     252     **                                      Modulus, 100%, MPa    1.54    1.77    **                                      Hardness, Shore A     58      58      **                                      Aging properties (70 hrs/275° C.):                                     Compression set       95      88.5    **                                      (70 hrs/200° C.), %                                                    ______________________________________                                         *The value of torque could not be measured because there was no change        between maximum and minimum values.                                           **The gumstock did not cure.                                             

The data in Table XVII show that a gumstock composition having a curingagent consisting of a diamine and a fluoroaliphatic sulfonamide only(Run 46) and a gumstock composition having a curing agent consisting ofa diamine, a fluoroaliphatic sulfonamide, and an organo-oniumaccelerator (Run 47) result in a cured gumstock having a high value ofcompression set. A fluorocarbon elastomer gum having this high of avalue of compression set would not be useful for preparing many shapedarticles.

The data in Table XVII also show that a gumstock composition having acuring agent consisting of a fluoroaliphatic sulfonamide and anorgano-onium accelerator only would not cure.

COMPARATIVE EXAMPLE B

The purpose of this comparative example is to show the properties of acured composition similar to, but not identical to, that described inU.S. Pat. No. 3,632,788. In this example, the fluoroaliphaticsulfonamide C₈ F₁₇ SO₂ N(C₂ H₅)H was used in place of thefluoroaliphatic sulfonamide C₈ F₁₇ SO₂ N(C₂ H₅)C₂ H₄ OPO(OH)₂. Thecomposition of Run 49 was analogous to the composition used inFormulation D of the example of U.S. Pat. No. 3,632,788. The compositionof Run 50 was identical to that of Run 49 with the exception that anorgano-onium accelerator was employed. The composition of Run 51 wasidentical to that of Run 50 with the exception that the amine curingagent was omitted. The identities and amounts of the various ingredientsare shown in Table XVIII.

                  TABLE XVIII                                                     ______________________________________                                        Curable gumstock Run no.                                                      ingredients      49        50      51                                         ______________________________________                                        FKM C, parts     100       100     100                                        Carbon black (N-990), phr                                                                      15        15      15                                         PbO, phr         20        20      20                                         DIAK No. 1.sup.a, mhr × 10.sup.3                                                         6.25      6.25    0                                          TPBPC.sup.b, mhr × 10.sup.3                                                              0         1.28    1.28                                       C.sub.8 F.sub.17 SO.sub.2 N(C.sub.2 H.sub.5)H,                                                 30.72     30.72   30.72                                      mhr × 10.sup.3                                                          Fluoroether A, phr                                                                             27        27      27                                         ______________________________________                                         .sup.a Hexamethylenediamine carbamate, .sup.+ H.sub.3 N(CH.sub.2).sub.6       NHCOO.sup.-                                                                   .sup.b Cure accelerator No. 1 in Table II                                

The compositions were mixed, press cured, oven cured, and aged under theconditions indicated in Table XIX. Curing characteristics and propertiesof cured gumstock are shown in Table XIX.

                  TABLE XIX                                                       ______________________________________                                                            Run no.                                                                       49    50      51                                          ______________________________________                                        Curing characteristics                                                        ODR, 177° C.:                                                          M.sub.L, N · m                                                                             0.34    0.45    0.23                                    M.sub.H, N · m, 12 min.                                                                    1.02    2.15    0.23                                    t.sub.sl, minutes     3.4     1.6     *                                       t.sub.5.6, minutes    *       *       *                                       Properties of cured gumstock                                                  Press cure properties (10 min/177° C.):                                Tensile strength, MPa 5.58    5.61    **                                      Elongation at break, %                                                                              310     261     **                                      Modulus, 100% MPa     1.03    1.23    **                                      Hardness, Shore A     47      49      **                                      Postcure properties (20 hrs/260° C.):                                  Tensile strength, MPa 7.68    6.71    **                                      Elongation at break, %                                                                              245     186     **                                      Modulus, 100%, MPa    1.95    2.14    **                                      Hardness, Shore A     55      49      **                                      Aging properties (70 hrs/275° C.):                                     Compression set       87      82      **                                      (70 hrs/200° C.), %                                                    ______________________________________                                         *The value of torque could not be measured because the difference between     the maximum and minimum torque was too low.                                   **The gumstock did not cure.                                             

The data in Table XVIII show that a gumstock composition having a curingagent consisting of a diamine and a fluoroaliphatic sulfonamide only(Run 49) and a gumstock composition having a curing agent consisting ofa diamine, a fluoroaliphatic sulfonamide, and an organo-oniumaccelerator (Run 50) result in a cured gumstock having a high value ofcompression set. A fluorocarbon elastomer gum having this high of avalue of compression set would not be useful for preparing many shapedarticles.

The data in Table XVII also show that a gumstock composition having acuring agent consisting of a fluoroaliphatic sulfonamide and anorgano-onium accelerator only would not cure.

EXAMPLE 8

The purpose of this example is to show that a curing agent consisting ofa polyhydroxy compound, an organo-onium accelerator, and afluoroaliphatic sulfonamide must be used to provide the benefits of thepresent invention. The gumstock composition of Runs 52 and 53 containeda curing agent consisting of a polyhydroxy compound, an organo-oniumaccelerator, and a fluoroaliphatic sulfonamide. The gumstock compositionof Run 54 contained a curing agent consisting of polyhydroxy compoundand an organo-onium accelerator, but no fluoroaliphatic sulfonamide. Thegumstock composition of Run 55 contained a curing agent consisting of apolyhydroxy compound, but no organo-onium accelerator and nofluoroaliphatic sulfonamide. The gumstock composition of Run 56contained a curing agent consisting of a polyhydroxy compound and afluoroaliphatic sulfonamide, but no organo-onium accelerator. Thegumstock composition of Run 57 contained a curing agent consisting of anorgano-onium accelerator and a fluoroaliphatic sulfonamide, but nopolyhydroxy compound. The identities and amounts of the variousingredients are shown in Table XX.

                                      TABLE XX                                    __________________________________________________________________________                          Run no.                                                 Curable gumstock ingredients                                                                        52  53  54  55  56  57                                  __________________________________________________________________________    FKM C, parts          100 100 100 100 100 100                                 Carbon black (N-990), phr                                                                           30  30  30  30  30  30                                  MgO.sup.a, phr        3   3   3   3   3   3                                   Ca(OH).sub.2, phr     6   6   6   6   6   6                                   TPBPC.sup.b, mhr × 10.sup.3                                                                   1.21                                                                              1.21                                                                              1.21                                                                              --  --  1.21                                Bisphenol AF.sup.c, mhr × 10.sup.3                                                            2.23                                                                              2.23                                                                              2.23                                                                              2.23                                                                              2.23                                                                              --                                  C.sub.8 F.sub.17 SO.sub.2 N(C.sub.2 H.sub.5)H, mhr × 10.sup.3                                 1.21                                                                              --  --  --  1.21                                                                              1.21                                C.sub.8 F.sub.17 SO.sub.2 (C.sub.2 H.sub.5)C.sub.2 H.sub.4 OPO(OH).sub.2,     mhr × 10.sup.3  --  1.21                                                                              --  --  --  --                                  __________________________________________________________________________     .sup.a MAGLITE D, commercially available from Merck                           .sup.b Cure accelerator No. 1 in Table II                                     .sup.c Curing agent No. 1 in Table I                                     

The compositions were mixed, press cured, oven cured, and aged under theconditions indicated in Table XXI. Curing characteristics and propertiesof cured gumstock are shown in Table XXI.

                                      TABLE XXI                                   __________________________________________________________________________                        Run no.                                                                       52  53  54  55  56  57                                    __________________________________________________________________________    Curing characteristics                                                        ODR, 177° C.:                                                          M.sub.L, N · m                                                                           1.69                                                                              1.69                                                                              1.69                                                                              1.24                                                                              1.24                                                                              1.81                                  M.sub.H, N · m, 12 min.                                                                  5.98                                                                              5.08                                                                              3.5 1.24                                                                              1.24                                                                              2.71                                  t.sub.sl, minutes   1.1 1.0 1.5 *   *   1.8                                   t.sub.5.6, minutes  3.8 *   *   *   *   *                                     Properties of cured gumstock                                                  Press cure properties (10 min/177° C.):                                Tensile strength, MPa                                                                             10.30                                                                             10.07                                                                             5.52                                                                              **  **  ***                                   Elongation at break, %                                                                            434 545 544 **  **  ***                                   Modulus, 100% MPa   2.5 2.06                                                                              2.03                                                                              **  **  ***                                   Hardness, Shore A   65  66  65  **  **  ***                                   Postcure properties (20 hrs/260° C.):                                  Tensile strength, MPa                                                                             12.40                                                                             10.93                                                                             6.75                                                                              **  **  ***                                   Elongation at break, %                                                                            286 375 467 **  **  ***                                   Modulus, 100%, MPa  2.77                                                                              2.38                                                                              2.26                                                                              **  **  ***                                   Hardness, Shore A   66  68  68  **  **  ***                                   Aging properties (70 hrs/275° C.):                                     Compression set (70 hrs/200°  C.), %                                                       35  42  70  **  **  ***                                   __________________________________________________________________________     *The value of torque could not be measured because the difference between     the maximum and minimum torque was too low.                                   **The gumstock did not cure.                                                  ***The gumstock did not cure sufficiently to form a molded product.      

The data in Table XXI show that in gumstock compositions wherein thecuring agents contained a polyhydroxy compound, an organo-oniumaccelerator, and a fluoroaliphatic sulfonamide (Runs 52 and 53), thevalue of compression set was sufficiently low to be acceptable forpreparing shaped articles. The data in Table XXI show that in a gumstockcomposition wherein the curing agent contained a polyhydroxy compoundand an organo-onium accelerator, but no fluoroaliphatic sulfonamide (Run54), the value of compression set was not sufficiently low to beacceptable for preparing shaped articles. The data in Table XXI showthat in a gumstock composition wherein the curing agent contained apolyhydroxy compound but neither an organo-onium accelerator nor afluoroaliphatic sulfonamide (Run 55), the composition would not cure.The data in Table XXI show that in a gumstock composition wherein thecuring agent contained a polyhydroxy compound and a fluoroaliphaticsulfonamide, but no organo-onium accelerator, the composition would notcure. The data in Table XXI show that in a gumstock composition whereinthe curing agent contained an organo-onium accelerator and afluoroaliphatic sulfonamide but no polyhydroxy compound, the compositionwould not cure sufficiently to form a molded product, thereby renderingthe property of compression set unmeasureable.

Various modifications and alterations of this invention will becomeapparent to those skilled in the art without departing from the scopeand spirit of this invention, and it should be understood that thisinvention is not to be unduly limited to the illustrative embodimentsset forth herein.

What is claimed is:
 1. Method of preparing a shaped article comprisingthe steps of:(a) providing a curable composition comprising at least onefluorocarbon elastomer gum, at least one polyhydroxy compound orderivative thereof as a curing agent therefor, at least onefluoroaliphatic sulfonamide as a curing agent for the fluorocarbonelastomer gum, an acid acceptor, and at least one organo-oniumaccelerator, the amount of said fluoroaliphatic sulfonamide curing agentbeing present in said composition in the range of about 0.0002 to about0.006 mole per hundred grams of said gum, said fluoroaliphaticsulfonamide curing agent being represented by the general formula:

    R.sub.f (A).sub.z SO.sub.2 NR(M.sub.1/x)

or

    R.sub.f '[(A).sub.z SO.sub.2 NR(M.sub.1/x)].sub.2

whereinR_(f) represents a monovalent fluoroaliphatic radical having from1 to 20 carbon atoms, R_(f) ' represents a divalent fluoroaliphaticradical having from 1 to 20 carbon atoms, A represents an organiclinkage, Z represents zero or one, R represents hydrogen atom or alkylradical having from 1 to 20 carbon atoms, and M represents hydrogen atomor salt forming cation with valence x, which is 1, 2, or 3, the amountsof said curing agents being sufficient to bring about cross-linking ofsaid fluorocarbon elastomer gum, (b) heating said composition to atemperature sufficient to cure said composition, and (c) recovering saidshaped article.
 2. The method of claim 1, wherein A is selected from thegroup consisting of --CR¹ R² --, --CR¹ R² CR³ R⁴ --, and --CR¹ ═CR² --,wherein R¹, R², R³, and R⁴ are selected from the group consisting ofhydrogen atom, fluorine atom, chlorine atom, and lower alkyl group. 3.The method of claim 1, wherein R_(f) represents a monovalentfluoroaliphatic radical having from 4 to 10 carbon atoms.
 4. The methodof claim 1, wherein R_(f) ' represents a divalent fluoroaliphaticradical having from 2 to 10 carbon atoms.
 5. The method of claim 1,wherein said fluorocarbon elastomer gum is a copolymer of vinylidenefluoride and at least one fluorine-containing olefin, and, optionally, afluorinated alkyl vinyl ether.
 6. The method of claim 1, wherein saidcomposition further includes a reinforcing agent.
 7. The method of claim1, wherein the total concentration of fluoroaliphatic sulfonamide curingagent and polyhydroxy curing agent in said composition is at least 0.001mole per hundred grams of said gum.
 8. Method of preparing a shapedarticle comprising the steps of:(a) providing a curable compositioncomprising:(1) at least one fluorocarbon elastomer gum, (2) at least onefluoroaliphatic sulfonamide as a curing agent therefor selected from thegroup consisting of C₈ F₁₇ SO₂ NR(M_(1/x)), C₈ F₁₇ C₂ H₄ SO₂N(R)(M_(1/x)), C₄ F₉ SO₂ NR(M_(1/x)), where R represents hydrogen atomor alkyl radical having from 1 to 20 carbon atoms, M represents hydrogenatom or salt forming cation with valence x, which is 1, 2, or 3, saidsulfonamide being present in the composition in the range of about0.0002 to about 0.006 mole per hundred grams of said gum, (3) at leastone organo-onium accelerator, and (4) at least one polyhydroxy compoundor derivative thereof as a curing agent for the fluorocarbon elastomergum, the amount of said curing agents being sufficient to bring aboutcross-linking of the fluorocarbon elastomer gum; (b) heating saidcomposition to a temperature sufficient to cure said composition; and(c) recovering said shaped article.
 9. The method of claim 8, whereinthe fluorocarbon elastomer gum is a polymer of vinylidene fluoride andhexafluoropropene.
 10. The method of claim 8, wherein the fluorocarbonelastomer gum is a polymer of vinylidene fluoride, hexafluoropropene,and tetrafluoroethylene.